A multilayer electronic device comprises a functional element consisting of an active part and two electrically conducting contacts, also called electrodes, on either side of this active part. Examples of multilayer electronic devices comprise in particular: organic light-emitting diode (OLED) devices in which the functional element is an OLED, the active part of which is designed to convert electrical energy into radiation; photovoltaic devices in which the functional element is a photovoltaic cell, the active part of which is designed to convert the energy from radiation into electrical energy; electrochromic devices in which the functional element is an electrochromic system, the active part of which is designed to switch reversibly between a first state and a second state having optical transmission properties and/or energy transmission properties different from those of the first state; and electronic display devices in which the functional element is an electronic ink system comprising electrically charged pigments that are capable of moving depending on the voltage applied between the electrodes.
As is known, irrespective of the technology employed, the functional elements of a multilayer electronic device are liable to be degraded due to the effect of environmental conditions, especially due to the effect of exposure to air or moisture. As an example, in the case of OLED or organic photovoltaic cells, the organic materials are particularly sensitive to the environmental conditions. In the case of electrochromic systems, electronic ink systems or thin-film photovoltaic cells comprising an inorganic absorber layer, the transparent electrodes, which are based on a TCO (transparent conductive oxide) layer or based on a transparent metallic layer, are also liable to be degraded due to the effect of environmental conditions.
To protect the functional elements of a multilayer electronic device from degradation due to exposure to air or moisture, it is known to fabricate the device with a laminated structure in which the functional elements are encapsulated with a front protection substrate and possibly with a back protection substrate.
Depending on the application of the device, the front and back substrates may be made of glass or an organic polymer material. An OLED or a photovoltaic cell encapsulated with a flexible polymer substrate, rather than a glass substrate, has the advantage of being pliable, ultra-thin and light. Moreover, in the case of an electrochromic system or a photovoltaic cell that includes an absorber layer based on a chalcopyrite compound, especially one containing copper, indium and selenium, called a CIS absorber layer, to which may optionally be added gallium (CIGS absorber layer), aluminum or sulfur, the device is conventionally assembled by lamination using an interlayer made of an organic polymer material. The lamination interlayer, which is positioned between an electrode of the functional element and the corresponding protection substrate, then makes it possible to guarantee proper cohesion of the device.
However, it has been found that, when a multilayer electronic device comprises an organic polymer lamination interlayer or an organic polymer substrate positioned against a functional element sensitive to air and/or moisture, the device has a high rate of degradation. This is because the presence of the organic polymer lamination interlayer, which tends to store moisture, or in the presence of the organic polymer substrate, which has a high permeability, promotes the migration of contaminating species such as water vapor or oxygen into the sensitive functional element, and therefore impairs the properties of this functional element.